The present invention relates to an instrument lifting operation device for an endoscope.
Endoscopes provided with an instrument lifting piece for controlling the protruding direction of the tip of a treatment instrument inserted into an instrument-insertion channel have been used. In such an endoscope, an instrument lifting operation device is provided in an operation unit to be operated by an operator. The instrument lifting operation device serves to remotely control the instrument lifting piece from the operation unit to which a proximal end of an insertion unit is connected.
In the instrument lifting operation device, an operation wire drawing mechanism for manually drawing a proximal end of an operation wire whose tip is connected to the instrument lifting piece is provided. In the state where the tip of the treatment instrument is lifted by the instrument lifting piece, a force for restoring the instrument lifting piece to an original state acts on the instrument lifting pieces from the treatment instrument.
In this case, when the operator releases the operator's finger from an operation member of the operation wire drawing mechanism, the operation wire moves back to the tip side of the operation wire by a drawing force acting on the operation wire from the instrument lifting piece, and thereby the instrument lifting pieces is restored to the state of not lifting the instrument lifting piece as described in Japanese Patent Provisional Publications No. H9-84757A and 2003-245248A.
In view of such a problem, Japanese Utility Model Provisional Publication No. S49-74788U (hereafter, referred to as JP S49-74788U) discloses a configuration where a braking mechanism for restring movement of the operation wire toward the tip side caused by a drawing force applied from an instrument lifting piece is provided in an operation unit.